Small Animal Soft Tissue Surgery Q&A 03

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The figure shows an eight-year-old male dog at exploratory surgery. The mass adjacent to the bladder was thin walled and filled with clear yellow fluid. There were several adhesions to the prostate, but an anatomic communication with the gland was not identified.

Question	Answer		Article
What is the most likely diagnosis?	Periprostatic cyst. The size of the cyst and the absence of communication with the prostate make this the most probable diagnosis.		Link to Article
What anatomic structure is thought to be involved in this process?	Periprostatic cysts are thought to arise from the uterus masculinus, a remnant of the Müllerian duct system. Serosal cysts and hemorrhage can also result in periprostatic cyst formation.		Link to Article
What are the surgical treatments for this abnormality, and what are the advantages and disadvantages of each?	Cysts resection is curative if the origin is identified. Disadvantages include more extensive prostatic manipulation needed to identify the origin of the cyst and recurrence in the case of inadequate resection. A recent report described good success using omentalization of the cyst remnant after subtotal resection. Marsupialization provides continuous drainage, and prostatic manipulation is minimized reducing the likelihood of damage to the prostatic neurovascular supply. The cyst is anchored to the paramedian rectus abdominus muscle. The cyst membrane is incised and the fluid drained and cultured. The cyst wall is then sutured to the skin to form a semi-permanent stoma. Disadvantages include difficulty in mobilizing the cyst to reach the abdominal wall and prolonged drainage. Resection is required if the cyst cannot be mobilized sufficiently. The stoma usually closes spontaneously by eight weeks postoperatively. Biopsy of the prostate and cyst wall and castration are performed at the time of resection or marsupialization to identify neoplasia and prevent recurrence of prostatic disease by inducing involution.		Link to Article